Echocardiography can help risk-stratify the severity of pulmonary embolism (PE) diagnosed in normotensive patients. However, because echocardiography is not uniformly available in U.S. hospitals, more accessible surrogate criteria are needed: to facilitate the immediate recognition of disabling PE in hemodynamically stable patients. Prior work by the Pi has led to the hypothesis that cardiopulmonary stress from severe PE can be recognized by abnormalities in vital signs, the 12- lead ECG and the serum troponin measurement. For this project, a screening instrument to rule out severe PE has been defined asthe combination of a shock index (pulse/systolic blood pressure) <0.8, a pulse oximetry reading >91 percent, a Daniel ECG score <8 points, and a troponin I <0.4 ng/mh The hypothesis of this project is that patients with a negative screening instrument will not have right ventricular (RV) strain on echocardiography and are at very low risk of death or cardiopulmonary disability from PE treated with standard: anticoagulation. The first specific aim of the project is to test the diagnostic accuracy of the proposed screening instrument, using RV strain on transthoracic echocardiography as the criterion standard. The second aim will compare the diagnostic accuracy of the screening instrument with echocardiography for the prediction of an adverse outcome from PE. Because the screening instrument may notpredict RV damage from recurrent or unresolved PE, the second hypothesis is that nonmalignant thrombophilic conditions will increase risk of an adverse outcomefrom PE. Accordingly, :the third aim will test if patients with PE complicated by an adverse outcome are more likely to have antiphospholipid antibodies, or factor V Leiden G1691A, prothrombin G20210A, methylenetetrahydrofolate reductase C677T mutations, or low red blood cell methylfolate or high :plasma homocysteine concentrations, compared with patients with PE and no adverse outcome. An adverse clinical outcome will include death or anoxic brain insult :within 30 :days of diagnosis, recurrent PE, or cardiopuimonary disability, determined six months after diagnosis. Cardiopulmonary disability will be defined by New York Heart Association functional class II or worse, a repeat transthoracic echocardiogram with persistent RV strain, and a six-minute walk distance less than 330 meters. This study will determine if criteria that are widely and immediately available in most hospitals can be used to risk-stratify severity of PE and to clarify the role of nonmalignant thrombophilias on the prognosis of PE.